Processes and compositions for scavenging hydrogen sulfide

Abstract

Processes and compositions for scavenging hydrogen sulfide from hydrocarbon streams are disclosed that reduce, if not substantially eliminate, the formation of crystalline or amorphous solids even under cold conditions. The compositions used in the processes comprise a hexahydrotriazine component and an amphiphilic component that form a hydrophobic micelle when the hexahydrotriazine component becomes spent.

Claims

1. A sulfhydryl scavenger composition comprising methylamine triazine and monoethanolamine triazine, wherein the amount of monoethanolamine triazine is sufficient to form a hydrophobic micelle with methylamine triazine in the presence of hydrogen sulfide and water; wherein the mole ratio of methylamine triazine to monoethanolamine triazine is between about 0.03 to 0.2:1.

2. A sulfhydryl scavenger composition comprising methylamine triazine and monoethanolamine triazine in which the mole ratio of methylamine triazine to monoethanolamine triazine is between about 0.03 to 0.2:1.

3. The composition of claim 2 further comprising at least one of water and methanol.

4. The composition of claim 1 further comprising at least one of water and methanol.

Description

EXAMPLES

(1) The following examples are for purposes of facilitating illustration of the invention and are not in limitation thereof. All parts and percentages are by volume unless otherwise stated or clear from the context.

(2) The following components are used in one or more of the following examples:

(3) Component A: MEA triazine product containing 82 percent 1,3,5-triethanol-s-hexahydrotriazine with the remaining 18 percent being composed of water and monoethanolamine available from Specialty Intermediates, Oklahoma City, Okla.;

(4) Component B: MMA triazine product purportedly containing a 33 percent active, aqueous solution of 1,3,5 trimethyl-s-hexahydrotriazine available from Weatherford International, Inc., Houston, Tex., as SulfaClear 8250; and

(5) Component C: MOPA triazine product containing an 84 percent active, aqueous solution of 1,3,5 (tris 3-methoxypropyl)-s-hexahydrotriazine prepared from 3-methoxypropylamine and formaldehyde.

(6) The water used in the compositions is deionized water.

(7) The following general procedure is used in the examples to evaluate scavenger compositions. A laboratory-scale bubble tower is used which has an inside diameter of about 20 millimeters and a height of about 60 centimeters. At the bottom of the bubble tower is a sparger that generates bubbles having a diameter of approximately 8 millimeters. About 10 milliliters of scavenger composition are placed in the bubble tower.

(8) A gas having an approximate composition of about 94.3 volume percent nitrogen, 5.1 volume percent carbon dioxide and 5900 parts per million by volume of hydrogen sulfide is passed to the sparger at a rate of about 0.40 Standard liters per minute. Although a hydrocarbon gas is not used for purposes of laboratory experiments, the use of the nitrogen and carbon dioxide-containing gas is believed to provide an indication of performance using a hydrocarbon gas.

(9) The temperature of the liquid in the bubble tower is at a temperature of about 25 C. The hydrogen sulfide content of the gas from the bubble tower is monitored by gas chromatography. The flow is continued until hydrogen sulfide breakthrough is observed by the gas chromatograph, and the spent scavenger solution is recovered for evaluation. The spent scavenger solution is visually inspected at about 25 C. In all instances, the spent composition is cooled to about 25 C. for at least 24 hours, and the cooled composition is again visually inspected.

Example 1 (Comparative)

(10) A scavenger composition is prepared using 50 parts by volume of component A and 50 parts by volume water. This composition is evaluated in the bubble tower and hydrogen sulfide breakthrough begins to occur after about 154 minutes, and the test is terminated at about 202 minutes. Initially the spent scavenger composition appears turbid. Amorphous solids are present in the cooled composition. The solids are not soluble in methanol and appear to be amorphous solids.

Example 2 (Comparative)

(11) A scavenger composition is prepared using 50 parts by volume of component C and 50 parts by volume water. This composition is evaluated in the bubble tower and hydrogen sulfide breakthrough begins to occur after about 137 minutes, and the test is terminated at about 162 minutes. The spent scavenger composition separates into to liquid phases with no solids being observed in the cooled composition. The denser liquid phase is analyzed by gas chromatography and mass spectroscopy (Rtx5 silica capillary column, Restek Corporation, Bellefonte, Pa., Varian Saturn 2000 GCMS, available from Agilent Technologies Inc., Santa Clara, Calif.) and is found to contain both the thiadiazine and the dithiazine derived from the MOPA thiazine. The thiadiazine to dithiazine mole ratio is not determined but is estimated to be in the range of 1:3 to 2:3.

Example 3 (Comparative)

(12) A scavenger composition is prepared using one hundred parts by volume of component B. This composition is evaluated in the bubble tower and hydrogen sulfide breakthrough begins to occur after about 217 minutes, and the test is terminated at about 234 minutes. Crystalline solids are observed before and after the composition is cooled. The solids are soluble in methanol and are crystalline solids from the spent MMA triazine.

Example 4 (Comparative)

(13) A scavenger composition is prepared using 50 parts by volume of component A, 25 parts by volume of methanol and 25 parts by volume water. This composition is evaluated in the bubble tower, and hydrogen sulfide breakthrough begins to breakthrough after about 129 minutes, the test is terminated at about 145 minutes. The spent scavenger composition appears to be a single liquid phase. When cooled, a few solids are observed.

Example 5 (Comparative)

(14) A scavenger composition is prepared using fifty parts by volume of component C, 25 parts by volume of methanol and 25 parts by volume water. This composition is evaluated in the bubble tower, and hydrogen sulfide breakthrough begins to breakthrough after about 160 minutes, and the test is terminated after about 186 minutes. Two liquid phases are observed in the cooled composition with the lower phase appearing turbid and without the presence of solids.

Example 6

(15) A scavenger composition is prepared using 25 parts by volume of component C, 50 parts by volume of component B and 25 parts by volume of methanol. In this composition, component C serves as the amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide breakthrough begins to breakthrough after about 89 minutes, and the test is terminated after about 154 minutes. Two liquid phases are observed. No solids are detected in the cooled composition.

Example 7

(16) A scavenger composition is prepared using 25 parts by volume of component A, 25 parts by volume of component C, 25 parts by volume of methanol and 25 parts by volume of water. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 177 minutes, and the test is terminated after about 194 minutes. Two liquid phases are observed. No solids are detected in the cooled composition. The denser liquid phase is analyzed by gas chromatography and mass spectroscopy (Rtx5 silica capillary column, Restek Corporation, Bellefonte, Pa., Varian Saturn 2000 GCMS, available from Agilent Technologies Inc., Santa Clara, Calif.) and is found to contain both the thiadiazine and the dithiazine derived from the MOPA thiazine and to contain the dithiazine derived from the MEA triazine.

Example 8

(17) A scavenger composition is prepared using 40 parts by volume of component A, 10 parts by volume of component C, 25 parts by volume of methanol and 25 parts by volume of water. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 177 minutes, and the test is terminated after about 194 minutes. A single liquid phase is observed. No solids are detected in the cooled composition.

Example 9

(18) A scavenger composition is prepared using 40 parts by volume of component A, 10 parts by volume of component C, 10 parts by volume of them ethylene glycol, 30 parts by volume of methanol and 10 parts by volume of water. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 162 minutes, and the test is terminated after about 178 minutes. A single liquid phase is observed. No solids are detected in the cooled composition.

Example 10

(19) A scavenger composition is prepared using 40 parts by volume of component A, 15 parts by volume of component C, 25 parts by volume of methanol and 20 parts by volume of water. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 202 minutes, and the test is terminated after about 2188 minutes. A single liquid phase is observed. No solids are detected in the cooled composition which has two liquid phases.

Example 11 (Comparative)

(20) A scavenger composition is prepared using 50 parts by volume of component B and 50 parts by volume of methanol. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 81 minutes, and the test is terminated after about 122 minutes. Crystalline solids are observed in the cooled composition.

Example 12

(21) A scavenger composition is prepared using 25 parts by volume of component A, 25 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 98 minutes, and the test is terminated after about 120 minutes. The liquid is turbid but a single phase to the naked eye. Solids are present before cooling and the amount of solids appears to increase after cooling.

Example 13

(22) A scavenger composition is prepared using 25 parts by volume of component A, 12.5 parts by volume of component B, 12.5 parts by volume of component C, 25 parts by volume of methanol and 25 parts by volume of water. In this composition components A and C serve as amphiphilic components. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 106 minutes, and the test is terminated after about 129 minutes. Two liquid phases are observed; however, the lower phase appears turbid but contains no observable solids before and after cooling.

Example 14

(23) A scavenger composition is prepared using 40 parts by volume of component A, 10 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 122 minutes, and the test is terminated after about 145 minutes. Two liquid phases are observed, and the lower phase appears clear with no observable solids before and after cooling.

Example 15

(24) A scavenger composition is prepared using 40 parts by volume of component A, 5 parts by volume of component B, 5 parts by volume of component C, 25 parts by volume of methanol and 25 parts by volume of water. In this composition components A and C serve as amphiphilic components. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 130 minutes, and the test is terminated after about 154 minutes. Two liquid phases are observed, and the lower phase appears clear with no observable solids before and after cooling.

Example 16

(25) A scavenger composition is prepared using 45 parts by volume of component A, 5 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 114 minutes, and the test is terminated after about 138 minutes. No phase separation is observed, and no solids are observable before and after cooling.

Example 17

(26) A scavenger composition is prepared using 42 parts by volume of component A, 8 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 138 minutes, and the test is terminated after about 162 minutes. A single liquid phase is observed; however, waves in the clear liquid are detected and are believed to be an indication of a separate observable liquid phase beginning to be formed. The lower phase appears clear after cooling with no observation of any solids.

Example 18

(27) A scavenger composition is prepared using 35 parts by volume of component A, 15 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 122 minutes, and the test is terminated after about 138 minutes. Two liquid phases are observed, and the lower phase appears clear with the presence of a slight amount of solids. The amount of solids observed did not increase after cooling.

Example 19 (Comparative)

(28) A scavenger composition is prepared using 30 parts by volume of component A, 20 parts by volume of component B, 25 parts by volume of methanol and 25 parts by volume of water. In this composition component A serves as an amphiphilic component. This composition is evaluated in the bubble tower, and hydrogen sulfide begins to breakthrough after about 122 minutes, and the test is terminated after about 145 minutes. Two liquid phases are observed, and the cooled composition appears to have solids.

(29) It is believed that the component be used in Examples 12 through 19 became partially deactivated due to extended storage.